Friday, January 16, 2009

This morning while walking across town to the Lady Killigrew, a small hipster café located just around the corner from home, I was thinking about a report I’d just begun to draft. The focus was how to evaluate the toxicity of nanoparticles. I was wondering if I’d been too strong in my dismal assessment of toxicology and had hoped that a good slap of cold air (the thermometer outside our kitchen window read -25C) would weed out the dramatic, and clarify the reality.

I’ve pasted some key points below, and while the topic and eventual report are confidential – there’s nothing confidential about the sentiment – I, and many others have been writing about it for a while:

1)The field of nanotoxicology is in its infancy, yet is ever expanding as newly created nanomaterials require assessment of potential health and environmental impacts.I’ve never before had the experience where I’ve considered research from 2006 as “old,” and where, the majority of literature cited is 2008 and 2009. Yet development of a new field within toxicology provides opportunity, and at the same time demands that toxicologists use both hindsight and foresight as they develop the methodology appropriate for these new materials.

2)Hindsight provides us with a glimpse of toxicology as a field, in large part, focused on application as a science catering to the need for rapid assessment and cost-effective regulation. Standardized toxicity testing methodology was developed and implemented as a result, quickly becoming a rigid set of test procedures, a good deal of which, over the years have become obsolete.

3)In part, because of the difficulties with changing test methodologies associated with a regulatory framework (check out the timeline for reproductive and developmental testing – “in development” for what, at least 10 years?) - standardized toxicity testing, useful for screening out the obvious is insufficient for detecting more subtle adverse effectsor revealing the impacts of the complex mixtures of contaminants, drugs and naturally occurring chemicals to which we are all exposed.

4)We have an opportunity to consider the history of toxicology as we move forward. Many have expressed concern that “business as usual” may result in failure to adequately evaluate toxicity of nanomaterials. Oberdorster et al., (2005) representing the International Life Sciences Institute Research Foundation/Risk Science Institute (ILSI/RSI) writes “There is a strong likelihood that biological activity of nanoparticles will depend on physicochemical parameters not routinely considered in toxicity screening studies.” Additionally different physicochemical parameters may also affect behavior of particles in media typically used in preparing for traditional toxicity testing, the ability of researchers to adequately evaluate exposure concentrations, and particle behavior in the body.Problems only occasionally encountered in the past.

5)When it comes to some nanomaterials, such as quantum dots and functionalized particles we’re potentially dealing with multiple organic and inorganic materials that may, or may not, be released over a period of time.How do we assess that?

Well, as I wondered if I was getting a bit too dramatic, after grabbing a cup of decaf and ordering a breadboard with mustard I settled in and checked my emails. Bingo. There in the inbox was a link to Peter Montague’s recent article entitled "Can Chemicals be Regulated?" published in Rachel’s Democracy and Health News. Read it and weep.

Or, read it and be hopeful.I really do think that we’re at the proverbial crossroads.We’ve seen the consequences of becoming too rigid, of constrained linear thinking.But this is a new multitasking interconnected networked “wisdom of the masses” kind of world, not just for me and my Lady K compatriots (the majority of whom – to the dismay of the management - are more attentive to their electronics than to their stomachs) but also for those laboring away in research laboratories around the globe.

Maybe I need another slap of cold air, but if we can embrace this new fluidity in information, knowledge, and thinking, perhaps we can embrace a new way of not only evaluating health and environmental impacts of new chemical products, but a new way of using that information wisely.

Toxicology: the study of the adverse interactions of chemicals with dynamic living systems.We are all exposed to a diversity of chemicals (often as chemical mixtures) through our diet, the pharmaceuticals we use, the air we breath, and the water we drink.While toxicologists usually study xenobiotics or chemicals “foreign to living systems,” it’s worth noting that in some cases, chemicals as familiar and as natural as water can be toxic.

Some history: Toxicology as a formally recognized scientific discipline is relatively new (mid 1900’s) although the science itself is thousands of years old. Consider the potential results of early trial and error experiences of hunter-gatherers for whom identifying a toxic plant or animal was a life or death situation.Some of the most poisonous substances known today are naturally produced chemicals including Ricin from castor beans or tetrodotoxin from the puffer fish. Early humans’ careful observation of plants or animals with toxic characteristics such as frogs containing curare, were put to use not only for avoidance of toxic substances but for weapons as well.Additionally, many naturally derived poisons were likely used for hunting, medicinals (the Egyptians were aware of many toxic substances such as lead, opium and hemlock as early as 1500 BCE), and eventually for the political poisonings practiced, for example, by the early Greeks and Romans.

As humans sought to better understand natural compounds that were both beneficial and harmful, there was very little if any clear understanding of the fundamental chemical nature of substances.That is, there was no connection between the ‘extract’ or ‘essence’ of a poisonous plant or animal and any one particular chemical that might cause toxicity.In fact, an awareness of chemistry in its modern form did not occur until the mid to late 1600’s[i].So it is ironic that Paracelsus, a physician from the sixteenth century and one of the early “Fathers of Toxicology” had no clear understanding of chemistry as we know it today.He along with many others at that time apparently believed that all matter was composed of three “primary bodies” (sulfur, salt, and mercury)[ii]. Yet Paracelsus also coined the now famous (or infamous) maxim of the newly emerging discipline of toxicology:

“All substances are poisons, there is none which is not a poison. The right dose differentiates a poison from a remedy.”(Paracelsus,1493-1541)

This phrase and Paracelsus’ name are committed to memory by hundreds of new toxicology students each year and has become the ‘motto’ of toxicology.Interestingly, if one takes Paracelsus at face value, it appears he was referring to potential remedies. This is an important point, since in recent years some have turned this around to suggest that exposure to very small doses of highly toxic chemicals (such as dioxins) might not be an problem! These days most of us are well aware of the fact that overdosing can turn remedies to poisons, even with apparently innocuous drugs such as aspirin and Tylenol.

About Me

I am an environmental toxicologist, writer, consultant, and mother of two children aged eleven and thirteen. My focus as a toxicologist is the impact of emerging contaminants on human health and the environment, particularly on aquatic systems. I write for local newspapers and journals, reporting and interpreting current research on environmental contaminants. I am also involved in the development and stewardship of the Encyclopedia of Earth (www.eoearth.org).
You can contact me at:
emonosson@verizon.net